I purchased my 1990 420SEl about 4 months ago. It has 80,100 miles on it. AT that time I had the oil changed among outher routine work. 4 months and 800 miles later, my oil light came on the other day. It went out after a short while. Oil pressure was holding at "3" @ 2000 RPM approximately. Engine was extremely quiet as it always has been. I checked the oil level when I got home. It was below the "min" on the stick. I added one quart of oil and it appeared to be probably 1 or 2 qts still short on the stick. There is absolutely no oil leaks, car is parked in garage. There is absolutely no oil smoking from exhaust. The only thing I can think of is I was short changed oil when it was changed 4 months ago. Am I correct in my assumption or should I be looking somewhere else? Appreciate any comments. Thanks, Tony.

I never fill mine above halfway between the min and max levels. I tend to loose oil if I do. Like you I have no smoke or drips. I say give it a while. Check it every weekend for a few weeks and if it is still going down you might want to get it checked out.

Thanks Jason. I'll monitor it. Tony